According to general manager Mike Rizzo, the trade is expected to be approved by the league office by Saturday. Guzman is a 10-and-5 player -- 10 years in the big leagues and five years with the same club -- and needed to approve the trade. He already packed his belongings in the Nationals' clubhouse.

"Guzzie was upbeat and positive," Rizzo said. "He obviously had to OK the trade, because he had 10-5 rights. It's not an official trade until the paperwork goes through. In 24 hours, it will be official by the Commissioner's Office."

Guzman, 32, is making $8 million in the final year of his contract this season. It is unclear whether or not the Nationals are taking on some of his remaining prorated salary.

Guzman, an original member of the Nationals, was hitting .282 with two home runs and 25 RBIs this season. He played most of the year at second base after playing his first 11 seasons in the Majors at shortstop.

With the Rangers, Guzman will initially play every day at second base because of an injury to Ian Kinsler. Once Kinsler returns to action, Guzman will be a utility player.

Prospect analysis

The Rangers needed a second baseman with the injury to Ian Kinsler, so they dealt for Cristian Guzman, giving up a pair of Minor League arms. Here's some more information on the newest Nationals pitchers, Tanner Roark and Ryan Tatusko:

Roark was a 25th round pick of the Rangers in the 2008 Draft. The 23-year-old right-hander made his full-season debut in the Class A Advanced California League in 2009, but moved up after going 10-0 with a 2.70 ERA in 29 games (nine starts). He went back to Double-A to start the 2010 season and has been in the Texas League all season, going 10-5 with a 4.20 ERA. He's primarily been a starter, with 17 of his 22 appearances in that role.

Roark has a near-average fastball that clocks in at 88-92 mph and typically sits in the 89 mph range. His secondary stuff lags behind. He has a loose, big curve that isn't sharp. His changeup is somewhat limited and he has average command. If the changeup comes on a bit more -- he has a feel for it, so it's possible -- he could be a back-end of the rotation type. If not, he could profile as a long reliever/spot starter.

Tatusko was taken by the Rangers in the 18th round of the 2007 Draft out of Indiana State. The 25-year-old right-hander was a Texas League All-Star pitching on the same staff as Roark. Through 100 innings, He was 9-2 with a 2.97 ERA. He's appeared in 24 games, 13 as a starter, moving into the rotation in May.

Tatusko features a good fastball, sitting at 91 mph and touching as high as 94 mph. He commands the heater pretty well, but a lack of life can hurt him at times. He's got a fringy-average curve and a fair changeup. His stuff plays up because of good feel and knowledge of how to pitch. The lack of fastball movement limits his ceiling, but he could be a back-end starter in the future.

-- Jonathan Mayo

Guzman is a free agent after the season, and the Nationals were not going to give him an extension. Guzman's best season in Washington was in 2008, when he hit .316 with nine homers and 55 RBIs.

"We decided to move Cristian to the Rangers," Rizzo said. "They needed an infielder with Kinsler going down. We have two good young Double-A prospects that will help our inventory -- two starting candidates. It's a trade -- veteran player for prospects."

With Guzman gone, the Nationals are going to have a platoon at second base between Adam Kennedy and Alberto Gonzalez. Kennedy, who started the season as the everyday second baseman and lost his job to Guzman by May, is hitting .252 with two homers and 17 RBIs.

Gonzalez has a .294 batting average with three RBIs in 67 games. He was given a chance to become the everyday second baseman last year, but he fell short, ending the season hitting .265 with a home run and 33 RBIs.

After the season comes to an end, trying to acquire a second baseman will be a top priority for the Nationals. There is a possibility that the team could go with Danny Espinosa by late next year.

In Tatusko, the Nationals get a highly touted pitching prospect. He has served as a starter and reliever, going 9-2 with a 2.97 ERA in 24 games -- 13 starts -- for Double-A Frisco.

Roark also played for Frisco, going 10-5 with a 4.20 ERA in 22 games -- 17 starts.

Tatusko and Roark will not be ready for the big leagues until possibly 2012.

Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.